WFG

I got a 15" Core 2 Duo Macbook Pro about two years ago (late May of '07) and have been very happy with it. Of course, after two years of constant use it is beginning to show it's age, so, I feel it's time to replace some parts. I'm mainly concerned with throwing in some more RAM and a new HD, but I also have a couple other questions.

Firstly, I'm considering both of these as they seem to be compatible and have generally favorable reviews:

HD: http://www.newegg.com/Product/Produc...82E16822145228
RAM: http://www.newegg.com/Product/Produc...82E16820231135

For the HD I was hoping to find one a little bit bigger. I found a 500GB Seagate but wasn't too thrilled with it and I think 320 is more then enough space, especially since I've got a few externals to back up a lot of my stuff on and my desktop.

I'm a bit more curious about the RAM. Apparently the most the laptop will see is 3GB (though I could've sworn it was 4 gigs ). Is this due to the OS or to physical limitations on the motherboard? I figure the full 4 would still help out for a Windows partition if I'm only being limited by the OS on the mac side and not the actual hardware, so I would still benefit from it.

That said-

Since I'm getting a new HD and will have to go about reinstalling everything, now feels like a good time to move up to Leopard, but with Snow Leopard coming out soon would it be a good idea to wait until that is out to do all of this? Is SL even going to be worth the wait or should I just install Leopard and be done with it?

Sorry if anything is confusing or stupid-sounding, I'm not very familiar with Mac's or laptops in general.

Thanks!